Contact-terminal construction



Jan.29,1929. 1,700,172

L. K. MARSHALL v CONTACT TERMINAL CONSTRUCTION original Filed Feb. 2e,1925 WITNESSES: INVENTOR ATTORNEY az/rance Afa/Ma Patented Jan. 29,1929.

UNITED STATES 'PATENT OFFICE.

Application led February 26, 1925;, Serial No. 11,895.

My invention relates to electric switches and particularly to contactmembers therefor.

One object of my invention is to provide a relatively simple andinexpensive contact terminal that shall embody a relatively small numberof parts.

In practicing my invention, I provide a bar of a base metal havingportions of reduced thickness on which are located metal portions ofhigh electrical conductivity, the thickness of the 'two metals havingbeen reduced by rolling to the desired final thickness.

In the single sheet of drawings,

Figure 1 is a top plan view of a thermostatic switch aggregate embodyingmy invention, a portion thereof being broken away,

Fig. 2 is a top plan view of an ingot employed in manufacturing thedevice embodying my invention, in its initial condition,

Fig. 3 is an end view thereof,

Fig. 4 is a top plan view of a composite bar after rolling,

Fig. 5 is an end view thereof, and

Fig. 6 is a top plan view of a finished contact member embodying myinvention.

A thermostatic switch aggregate 11 comprises a base portion 12 of asubstantially circular metal member, upon whichv is located a circulardisk 13 of a suitable insulating material, such as mica. A plurality ofi contact members 14, 15, 16 and 17, are held against t-hc upper surfaceof the insulating disk 13 by suitable means comprising rivet members 1Sfor each of the respective segments.

The thermostatic disk 19 is of the kind disclosed in Patent No.1,491,363, issued April-22, 1924, to 'J A. Spencer. This disk issupported on the circular base plate or member 12 by a through-lm'lt 21and a cooperating nut 22 mounted thereon.

` A plurality of contact bridging members, comprising disks 23, aresecured to the thermostatic disk in spaced position adjacent to theperiphery t-hereof` and insulated therefrom and in such position thatthey will operatively engage the adjacent end portions of pairs of therespective fixed contact members 14 to 17, inclusive. i

The construction and mounting of the contact bridging members is notfurther CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO SPENCER OF CAMBRIDGE,MASSACHUSETTS, A CORPORATION OF CONTACT-TERMINAL CONSTRUCTION.

Renewed November 11, 1927.`

described in the present application, as it forms no part of myinvention.

The method of manufacturing the contact or terminal plates is asfollows: A relatively heavy bar or ingot 24, illustrated in Figs. 2 and3 of the drawing constitutes the base of the member. This bar mayconsist of platers bronze or of Monel metal. An intermediate bar 25,either of platers bronze or of Monel metal has clamped thereagainst, ateach side, bars 26, and 27 of silver, and relatively thin bars 28 and29, of bronze or of Monel metal, are clamped against the outside.surfaces of the silver bars. All of the bars 25 to 29 inclusive are ofthe same height and are brazed together, thin strips of silver solder orof phosphor bronze being placed between the contacting surfaces to edectproper brazing. The compound bar thus constituted is then brazed againstone surface of the bar 24, a strip of either phosphor bronz or of Monelmetal being placed therebetween to assist in the brazing operation in amanner well known in the. art. The bottom surface of the ycompound barcomprising bars 25 to 29 inclusive may be ground smooth in order thatthe brazing operation may be properly carried out.

I have obtain d satisfactory results by employing a ba 24 approximatelythreefourths inch tltck and one and one-eighth inches wide. 1e bar 25 isapproximately one-half inch i ide, the bars 26 and 27 are approximatelyone-fourth inch wide, and the bars 28 and 29 are approximatelyonesixteenth inch wide. The depth of these bars is approximatelyone-fourth inch. lVhile I have given specic dimensions, I do not desireto be restricted thereto as these are illustrative and proportional onlyand may be departed from.

rlhe cmnposite bar is cold rolled longitudinally thereof a suflicientnumber of times, and, is also annealed a plurality of times in order tomaintain the materials in proper condition to be reduced in thicknessand to be increased 'in length, as well as, to a lesser extent, inwidth. The general shape' of the composite bar after the rollingoperations is indicated in top plan view in Fig. 4, and in end view inFig. 5 thereof and it may be noted particularly that the depth of thesilver inserts 26 and 27 constitutes an appreciable portion of the totaldepth of the base member bar, there designated by the numeral 3l toindicate that it has changed its dimensions from those shown originallyfor the bar 24. The thickness of the member 31 is approximately l/32.

Fig. 6 of the drawing illustrates an arcuate contact member or plate 15that has been punched from the rolled composite bar, illustratedparticularly in Fig. 4 of the drawing Where I have indicated an opening32 there-- in from which a plate l5 has-been punched. The. broken lines33 indicate the portion of the composite plate that is removed by eachpunching operation, a central opening 34 being provided therein forreceivingr the holding means 18 in the respective terminal plates.

It may be noted that the edge portions of the intermediate portions ofthe base metal 29 extend in parallel spaced relation to each other, byreason of the hereinbefo-re described construction and method ofrolling, which comprised, as hereinbetore described, passing the samelongitudinally of its length between suitable rollers to increase thewidth of the intermediate portion of the original bar 24 to a limitedextent only, and to increase the length thereof to a relatively largedegree, and reduce the thickness.

The device embodying my invention thus provides a relatively thincomposite bar that has a contact portion of silver, of an appreciabledepth, at the end portion thereof or that may be located at anyintermediate portion of the Contact plate, as may be desirable. In theparticular application illustrated, it is necessary that the contactportions beat the ends thereof. The contact portion of the respectiveterminal plates are located in what ma be termed either a shoulderportion, in t 1e finished device or in a groove in the semi-iinishcddevice, which portion is of large depth relatively to the thickness ofthe supporting plate that is of base metal whereby a long life of thecontact portion or portions is ensured.

Since various modifications and changes may be made without departingfrom the spirit and scope of the invention. I desire that only suchlimitations shall be placed thereon as are imposed by the prior art.

I claim as my invention:

l. The method oflnaking contact terminals which comprises brazing acentral and two side bars of a base metal with two intermedia-te bars ofa highly-condnoting niet-al, brazing the composite bar on a base metalbar, cold rolling the bar thus formed to a relatively thin elongatedsheet, and punching contact terminals therefrom having spaced apartportions thereof of highlyconducting meta.

2. The method of making cont-act termi nal members which comprisesbrazing together alternatebars of a base metal and a highly-conductingmetal, brazing said composite bar on a base metal bar, subjecting all ofsaid bars to repeated cold rolling and annealing operations to decreasethe thickness and increase the length of said bar without substantiallyincreasing the width thereof, and then so punching contact terminalmembers therefrom that spaced apart portions of the surface thereof willbe of highly-condueting metal to constitute .the contact surfaces.

3. The method of making contact terminal members which comprises brazingtogether alternate bars of a base metal and a highlyconducting metal,brazing said composite bar on a base metal bar, subjecting all of saidbars to repeated cold rolling and annealing operations to reduce thethickness thereof to a predetermined value, and then punchingl contactterminal members therefrom, said terminals comprising a base portion ofbase metal and a top portion having an intermediate portion of basemetal and end portions of highly-conducting metal.

4. 'The method of making contact terminals which` comprises brazing acentral and two side bars of a base metal with two intermediate bars ofa highly conducting metal to form a composite bar, brazing the compositebar on a base metal bar, cold rolling the bar thus formed to arelatively thin elongated bar, and punching contact terminals therefrom,said terminals comprising a base portion, and a top portion having endportions of highly conductive metal and an intermediate base metalportion.

5. A contact terminal comprising a top portion having two side portionsof highly conducting metal, said metal being substantially resistant tooxidation, and anl intermediate portion of a base metal, and a bottomportion of base metal, all of said metals being united to form anintegral compound metal member. l l

6. The method of making a composite bar which consists in permanentlyjoining two bars of a highly conducting metal to a base metal, thehighly conducting bars of metal being-disposed on opposite sides of thebase metal, similarly joining base metal bars on the free sides of t-hehighly conducting metallic bars, and joining a base metal member to thebottom of all of the bars.

7. The method of claim 6, and in addition. thereto, cold rolling thecomposite bar to a relatively thin elongated sheet. j

8. The method of claim 6, and in addition thereto, cold rolling thecomposite bar to a relatively thin elongated sheet and punching -outportions thereof.

9. A composite bar of metal comprising a .f central portion of basemetal with a portion of highly conducting metal on each side of thecentral portion and a portion of base metal on each side of the highlyconducting port-ion and a broad portion of base metal in 'Contact withall of the portions, the different metals being permanently joinedtogether at their contact surfaces.

10. The bar of metal as described in claim .9 in which the highlyconducting portions of metal are resistant to oxidation and corrosion.

11. A composite bar ofl metal comprising a central portion of base metaland alternate' portions of highly conducting and base metal portionsoneach side of thev central portion with a single supporting layer ofmetal for all the portions, the various elements being permanentlyJoined together into one bar oi' metal.

12. A Contact terminal conrnprising two separated portions of highlyconductngf material each vone having a side flanked by a portion ofdierent material and all supported by another portion of material, allpermanently joined together. u

13. A Contact terminal comprising two separated portions of highlyconducting material with tWo portionsof a different material so joinedthereto that one portion of the latter material separates the first twonamed port-ions While the other portion-of4 the latter material joinsthe `nst named two portions,

In testimony whereof, I have hereunto 'subscribed my'name this 20th dayo' February, 1925.

. LAURENCE K. MARSHALL.

